ref: 5a2ea91cad4dd34fb766498a032294eb3c7a09b2
dir: /html/dominosa.html/
Dominosa <p> Tile the rectangle with dominoes (1×2 rectangles) so that every possible domino appears exactly once (that is, every possible pair of numbers, including doubles). <p> Click between two adjacent numbers to place or remove a domino. Right-click to place a line between numbers if you think a domino definitely cannot go there. Dominoes light up red if two identical ones appear on the grid.